1. Field of the Invention
The present invention relates to an optical system, and more particularly, to a subminiature optical system mounted on a mobile communication terminal and a personal digital assistant or used for a monitoring camera and a digital camera.
2. Description of the Related Art
In general, early mobile communication terminals have only a communication function. However, as use thereof is increased, various services such as photographing, image transmission, and Internet, etc are provided, thereby continuously developing functions and services thereof. Recently, mobile communication terminals of a new extended concept, such as, so called, camera mobile phones come in to the spotlight, where techniques for digital cameras and mobile phones are integrated.
Particularly, with respect to an optical system mounted on a camera mobile phone, a small size, light weight, and low price are required. Also, as a pixel size of an image sensor such as a charge-coupled device (CCD) or complementary metal-oxide semiconductor (CMOS) becomes smaller and smaller, a high resolution is required in an optical system using such image sensor.
Also, to satisfy a small size and low price, it is required to reduce a number of lenses of an optical system mounted on a small device such as a mobile phone. However, there is less degree of freedom in design and it is difficult to satisfy optical performance thereof.
Also, when an optical system including a plurality of refractive surfaces, a number of refractive surfaces to be managed when manufacturing and assembling lenses is increased, thereby complicating a lens manufacturing process and increasing manufacturing costs.
Accordingly, there is required a subminiature optical system capable of reducing a size thereof and easily mounting lenses thereon while having a high resolution and less aberration.